With regard to such a BBW type brake device, an arrangement in which a slave cylinder that is actuated by an electrical signal corresponding to an amount of operation of a brake pedal to thus generate a brake fluid pressure is formed from a cylinder, a piston slidably fitted into the cylinder, a motor, and a speed reduction mechanism that reduces the speed of rotation of the motor and converts it into reciprocating movement of the piston is known from Patent Document 1 below.